The invention relates to a shift device for the drive of a utility vehicle, in particular an agricultural tractor, the shift lever of which is used for shifting a multi-stage transmission, in particular a stepped gear change transmission, and additionally has a further change-over shift function which can be used in all ranges or stages, in particular for a load shift stage, wherein the shift lever, which is mounted pivotally in two directions, can be brought into and out of engagement with the shift segments which act on the transmission by way of further shift members (for example, angle lever, linkage, shift shafts), and use thereof for installation in a utility or working vehicle, in particular an agricultural tractor.
In the art of agricultural vehicles, in particular in agricultural tractors, drive shift devices are known which have two shift levers which are arranged adjacent to each other and of which one serves as the so-called gear or stage shift lever, for example, three or four speed stages, (forward or reverse), while the other serves as a range or group shift lever for one or more forward ranges and reverse range. Then, for example, when there are two forward ranges, this arrangement gives eight speed stages forward and four speed stages in reverse. In the course of providing vehicles with increased drive comfort and optimum adaptation to the grond or travelling and working conditions, such vehicles may additionally be provided with a so-called fast-slow change-over shift function which can be shifted under load, whereby, with a reduction in speed of, for example, 20%, the traction force may be increased in the corresponding gear stage by, for example, 25-30%, and vise-versa. The above-mentioned function has hitherto been performed with an additional shift lever which is generally arranged on the steering wheel and which from there acts, by means of a separate linkage arrangement, on hydraulic valves of the planetary transmission associated with the main transmission.
Analysis of the experience which has been acquired in dealing with vehicles provided with such shift arrangements shows that further combining, in particular, shift and/or clutch functions in a single shift lever, affords considerable advantages from the point of view of operation. This applies, in particular, in regard to integration of the above-discussed fast-slow function for two speeds of rotation, with the gear shift lever.
The present invention is therefore based on the problem of providing a shift device of the above-indicated kind, wherein the novel simplification in operation is to be achieved in a cost-effective and also robust and low-maintenance manner. The shift device should be of such a nature that, in use thereof, it can be disposed in a space-saving manner and in such a manner that it can be comfortably and conveniently gripped, in particular in the vicinity of the side wall of a driving cabin.